Ultra-wide Band (UWB) wireless communication technology has been widely used in the field of localization because of its signal characteristics and technical advantages. However, the increase of the nodes in networks will lead to channel contention. We design a multi-access scheme (two-frame scheme) for UWB localization networks to solve this problem. Using this scheme, each node can obtain the distance between the node and other nodes by sending two frames. Using the distance information, the network topology can be calculated. We also offer the solution for frame loss and multi-hop networks. Finally, the two-frame scheme is verified by simulation.